Antipercolating device



Oct. 7, 1952 w. E. EGERER ETAL ANTIPERCOLATING DEVICE Filed Jan. 19, 1950 WWW IN V EN TORS HTTOIQNFY Patented Oct. 7, 1952 v 2,613,068. l i it AN'rIPEaooLATInupiivicn William E. Egereflllarry B. Medley, Milton .J Kittler, Detroit, Mich, assignorscto George Mildclley and llarl Holley, a.

The object of this invention is to eliminate the vapor lock and percolation troubles which occur in a conventional downdraft type of carburetor due to the flow of heat from the manifold and other adjacent hot portions of the engine into the float chamber of a downdraft carburetor. When an automobile or truck equipped with such a carburetor is driven for a period. of time in hot weather, especially under conditions of high speed or heavy load, a great deal of heat is stored up in the engine and the intake and exhaust manifolds. If the car is then stopped and shut off this heat is carried by conduction and radiation into the float bowl of the carburetor where it causes boiling of the fuel wherever it contacts the heated metal portions of the carburetor. This boiling occurs in the carburetor metering passages where it induces percolation which results in extremelydiflicult starting, since the hot manifold becomes loaded with fuel which has percolated out of the carburetor. The extreme- 1y high temperatures reached in the carburetor fuel passages also cause vapor lockin of these passages after the engine has been restarted. Much work has been done to correct this type of trouble and many devices have been tried, some of which have enjoyed a measure of success, but none have been altogether satisfactory. We have discovered that if we simplylocate the fuel metering passages and orifices in the float chamber in such a manner that they are completely surrounded by fuel, that percolation and vapor lock troubles can be completely eliminated without the need for special gadgets. The principle is somewhat that of a well known double boiler used in every kitchen. By having the fuel metering passages arranged in the form of dependent tubes completely submerged in the fuel in the float chamber, it is impossible to raise the temperature of the fuel in these passages above the temperature of the fuel in the bowl. This inanifestly makes it impossible to transmit to the fuel in said dependent passages sufiicient heat to provide the latent heat of vaporization required to boil the fuel in such passages. The possibility of percolation and vapor lock is therefore, overcome. Fuel still will boil to some extent in the float chamber itself, but this boiling is not serious since it is only where fuel is trapped in thecarburetor metering passages that percolation and vapor lock result.

In the case of the accelerating pump a check valve positively traps the fuel between the accelerating pump piston and the accelerating fuel outlet. Hence, the fuel is positively forced into 2 the heated inlet manifold where it flashes into vapor and produces the non-combustible mixture which is one of the causes of vapor trouble.

Fig. 1 shows the preferred form of our invention with the location of parts distorted slightly to make the drawing clear and in one plane.

Fig. 2 is the elevation of the gasket interposed between the metering element and the body of the carburetor.

Fig. 3 is a view taken looking at the metering element when removed from the float chamber.

In Figs. 1, 2, and 3 the choke valve H2 is located in the throat of the venturi I I4 immediately downstream of the air entrance H6. A float chamber I26 supplies fuel to the fuel orifice 2m in a dependent element 250. A low speed passage 251 communicates with the bottom of the well 252 and allows the low speed fuel to pass in through the passage 253 and down the vertical passage 254 to the two outlets 255-456. An air vent 251 breaks the syphon 25 [-254 which would otherwise exist. Fig. 1 is the subject matter of Patent No. 2,538,569, issued January 16, 1951, which illustrated the feature to the left of choke shaft Ill.

The main fuel is supplied through the inclined pass-age 262 which is downstream of the choke shaft H I into the throat of the venturi. l4. An air vent 266, consisting of a lon narrow tube, dips down into the well 252.

A rod 322 and a spring 258 engages the upper end of a valve I2 I. A restriction 324, between the valve [2| and the restriction 2l9, provides the extra fuel necessary for maximum power, wide open throttle. A flange 261, extending laterally from the element 256, is held to th main body of the carburetor by cap screws, which screws compress the gasket 266. This gasket serves as a barrier to the restrictions 2l9 and 324. A throttle H6 controls the flow of mixture to the inlet manifold where the fuel is heated by the jacket Operation After an engine has stopped running, the heat from jacket I86 (the exhaust manifold) flow up past the inlet manifold I88 into th float chamber and raises the temperature of the fuel around the element 256 to the point where bubbles of vapor are released and escape from a vent in the float chamber cover. Fuel free from bubbles. however, is available at the point 2l9 through which the fuel flows to the nozzle. Heat can only flow into the element 250 by flowing through the gasket 266 so that by the time the heat reaches the casing containing the nozzles, time has elapsed and the engine generally has cooled down. With this construction, we have found the engine will restart immediately, regardless of the time; whether one minute or twenty minutes since the engine has stopped.

What we claim is:

In a downdraft carburetor for an internal combustion engine, a constant level fuel supply chamber, an L shaped element, separate from and independent of the said chamber, the vertical leg consisting of an air vented well having a restricted fuel entrance, the lower horizontal leg carrying an automatic valve adapted to admit additional fuel to the well, engine suction operated means actuating said valve, 2. flange on the upper end of the vertical leg, said flange being bolted to the inside of the fuel supply chamber,

low and high speed fuel passages through said 4 flange, engine suction means for drawing the fuel through both sets of fuel passages.

WILLIAM E. EGERER. HARRY B. MEDLEY. MILTON J. KITTLER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,575,877 Tice Mar. 9, 1926 2,103,629 Moore Dec. 28, 1937 2,162,056 Bracke June 13, 1939 2,186,480 Ensign Jan. 9, 1940 2,358,435 Ball Sept. 19, 19514 2,407,095 Olson Sept. 3, 1946 2,415,491 Hieger Feb. 11, 1947 

